On remote sub-Antarctic islands in the Southern Indian Ocean grows one of the world’s most isolated plants – the Kerguelen cabbage (Pringlea antiscorbutica).
Adapting to extremes
The Kerguelen cabbage, an evolutionary curiosity, as its name suggests, belongs to the Brassicaceae family (broccoli and cabbages) yet is separated from its nearest relatives by thousands of kilometres. As a result of the isolation, this native Australian plant has evolved highly specialised adaptations allowing it to thrive in some of the most extreme conditions in the world.
The Kerguelen cabbage is exposed to persistent sub-zero temperatures, strong winds, salt spray, sea flooding, and nutrient-poor soils. This plant resembles the common cabbage with thick, leathery leaves forming rosettes. Its tough leaves allow it to withstand high winds and abrasion from wind-driven particles, while also helping to reduce water loss. The cabbage also has high levels of ascorbic acid (vitamin C) and associated glucosinolates in response to cold stress and high UV exposure. These function as antioxidants that protect plant tissues from cell damage.
Because insect pollinators are virtually absent from sub-Antarctic islands the species has evolved to self-pollinate or wind pollinate. It takes approximately 3–4 years to reach reproductive maturity, after which it produces tall flowering stalks and large, lipid-rich seeds. These seeds provide the energy needed for germination in a low-nutrient environment.
An ecosystem engineer
On the tree-less sub-Antarctic islands, the Kerguelen cabbage is among the largest plants present, often being up to a meter in diameter. Its growth form helps stabilise soil, buffer wind, and trap moisture, creating small but important microhabitats. These niches support native invertebrates, including the fly Calycopteryx mosleyi and the weevil Ectemnorhinus viridis.
A botanical remedy
The plant is also notable for its historical significance due to its naturally high vitamin C content. During 18th–19th century voyages, including those led by James Cook, it was used to prevent and treat scurvy among sailors in the Southern Ocean. The same compounds linked to vitamin production give the plant a sharp, peppery taste.
Future in a changing environment
The sub-Antarctic Islands that the Kerguelen cabbage calls home are undergoing rapid changes including high temperatures, reduced water availability and extensive deglaciation. Physiological studies show that while the Kerguelen cabbage is extremely well adapted to the cold, it is also very sensitive to warming and water stress. These pressures cause its leaves to wilt and scorch. Furthermore, the establishment of invasive species which predate on the Kerguelen cabbage has increased. These challenges are causing concerns about the survival of this amazing plant, but a lack of research about how climate change will impact where this plant will or won’t be able to survive in the future hinders its conservation.
Heard Island – A living laboratory
In 2026, for the first time in 20 years, scientists from SAEF visited Heard Island to survey the presence of the Kerguelen cabbage, along with other native vegetation. Using this information about the cabbages current distribution, they will use models to predict how Kerguelen cabbage presence and distribution may respond under different climate change scenarios. This information can also be used to assess the species likely risk of extinction.
Heard Island is of particular interest because not only is the current state of vegetation on the island largely unexplored, but it is at the very limit of the Kerguelen cabbage’s range and the coldest place in which it exists. Heard Island’s isolation, minimal historical human disturbance, and status as a World Heritage Site make it one of the most ecologically pristine islands globally. Unlike other sub-Antarctic islands where Kerguelen cabbage exists, Heard Island lacks a presence or history of introduced and invasive predators, offering a rare opportunity to study the cabbage in an environment where climate change is the primary ecological driver of change.
Furthermore, because the sub-Antarctic environment is one of the fastest changing environments in the world, this means what we learn on Heard Island can be used as a ‘sneak-peak’ into the future, allowing scientists to anticipate ecological responses to global change in other regions.
Author
Maddison Farrant is a SAEF PhD candidate based at Monash University
Further Reading
- Dorne, A.J. & Bligny, R. (1993) Physiological adaptation to subantarctic climate by the Kerguelen cabbage, Pringlea antiscorbutica R. Br. Polar Biology. 13, 55–60. https://doi.org/10.1007/BF00236583
- Hartley, K.H., Guy, P.L., Lord, J.M. (2024) A tale of two species: Pringlea antiscorbutica and Azorella polaris, sub-Antarctic scurvy remedies. Polar Record. 60, e7. https://doi.org/10.1017/S0032247424000019
- Thieret, J. W. & Young, S. B. (1988) The Kerguelen-Cabbage, Pringlea antiscorbutica (Brassicaceae). Economic Botany, 42(2), 288–291. http://www.jstor.org/stable/4255079
